tools: NeuVector: introducing NeuVector (REST) scan type

[pna-nca]

This commit adds the support of NeuVector (https://github.com/neuvector/neuvector) tool for importing scan results. Scan results can be exported via REST API in JSON format (that is why the tool is named 'NeuVector (REST)'). There is no GUI for that at the moment.

Scan results are just a list of issues found in packages installed in a container or an image. Very similar to Twistlock.

NeuVector also provides compliance scan results. This is not supported by the introduced tool.

[kareem-DA]

I could use this. Thanks for adding